For some forecasters gathered at the National Hurricane Center’s annual conference this week, last season proved a painful reminder of just how tricky their jobs can be.

“It’s hard to go all these years and then make your worst forecast after 30 years,” climatologist William Gray, 84, the man who pioneered the science of pre-season predictions, told the packed room. “It’s not very good progress.”

Last week, Gray, founder of Colorado State University’s Tropical Meteorology Project, and colleague Philip Klotzbach, released their closely watched forecast for 2014, which calls for just three hurricanes, with only one becoming a major storm reaching Category 3 or higher.

The annual forecast from Gray and Klotzbach — followed by a handful of other expert predictions, including from the federal government — has become the opening bell for the upcoming hurricane season, which begins on June 1.

But for the past two years, predictions have been off — way off in the case of 2013, which Gray called a “bust.” Colorado State had predicted an active season, with 18 named storms and eight to nine major storms. Instead, it was slow, with 13 named storms and only two hurricanes.

Learning from experiences — both failures and successes — is a big reason forecasters hold the annual conference, said Hurricane Center director Rick Knabb. This year’s was staged at the Hilton Orlando.

Technology and ever-improving computer models have dramatically improved the ability to forecast the paths of storms once they have formed. But as last year illustrated, there are still gaps in long-range, pre-season predictions.

“There is still often a misconception that the seasonal activity, and therefore the seasonal forecast, can tell us what we’re going to experience in Florida,” Knabb said. “And that’s just not the case, because you can have a very above-average year and not have any hurricane [damage] and have a below-average year and have Andrew [which devastated South Miami-Dade in 1992].”

In fairness, just about everyone else in the pre-season prediction business also overshot the mark last year — including the annual predictions from Florida State University, Columbia University and the federal government’s National Oceanic and Atmospheric Administration.

On Tuesday, Gray attributed the botched forecast to the dramatic weakening of a deep current called the Thermohaline Circulation that carries denser, saltier water from the earth’s polar oceans. When it’s strong, more hurricanes tend to form.

The current’s collapse last year, Gray said, was the biggest observed since 1950.

“This is another illustration of how brilliant meteorologists are — after the fact,” he joked. “I’ve been working very hard the last three or four months to explain our bust. So we’ve eaten our crow, especially me.”

Making matters trickier is the inability to predict the current, which scientists describe as the ocean’s conveyor belt, said Klotzbach, also a Colorado State climate researcher.

“You can’t really see it until it’s happening. That’s the problem,” he said.

Forecasters basically use two models to predict storms.

Gray and Klotzbach rely on historical data and statistics.

NOAA and FSU create climate models that use existing sea temperatures and crunch more than 200,000 lines of computer code during the week leading up to the season to factor in atmospheric conditions like wind speed, rainfall, sunlight and cloud cover collected in 100-by-100-kilometer grids across the globe, said Tim LaRow, an associate research scientist at FSU’s Center for Ocean-Atmospheric Prediction Studies.

“It incorporates all the physical understanding that we have of the atmosphere,” he said. “And it gives us the equations of motion to calculate the flow of the air.”

In the six years LaRow has been running the complex climate model — which NOAA’s Miami chief of hurricane specialists, James Franklin, described as one of the most reliable around — it has been about 70 percent accurate. But 2013 also foiled the model, even when he ran it again using actual conditions.

“Last year was just one of those climate flukes, that no matter what we do we wouldn’t be able to model it correctly,” he said.

Gray’s current theory could be the explanation, he said. Or, he added, “there was something in the climate system we don’t know about and don’t have in our models.”

“We just see a lot more westerly winds near the International Date Line, and that’s a pretty good tip-off of an El Niño event,” he said.

But a quiet forecast can create an additional problem for emergency managers: apathy in the wider population.

“It is much easier if the prediction is for an active season to get people to pay attention. So it will be a challenge this year,” said Bryan Koon, the state of Florida’s emergency management director, who was sitting in the front row for Gray’s forecast. “But as you also hear them say, there have been an awful lot of storms that start with the letters A, B and C in Florida and elsewhere that have catastrophic damage.”

Never miss a local story.

Sign up today for a free 30 day free trial of unlimited digital access.